ID 1.2.1.25 DE branched-chain alpha-keto acid dehydrogenase system. AN 2-oxoisovalerate dehydrogenase (acylating). AN branched-chain alpha-keto acid dehydrogenase complex. CA 3-methyl-2-oxobutanoate + CoA + NAD(+) = 2-methylpropanoyl-CoA + CO2 + CA NADH. CC -!- This enzyme system catalyzes the oxidative decarboxylation of CC branched-chain alpha-keto acids derived from L-leucine, L-isoleucine, CC and L-valine to branched-chain acyl-CoAs. CC -!- It belongs to the 2-oxoacid dehydrogenase system family, which also CC includes EC 1.2.1.104, EC 1.2.1.105, EC 1.4.1.27 and EC 2.3.1.190. CC -!- With the exception of the glycine cleavage system, which contains 4 CC components, the 2-oxoacid dehydrogenase systems share a common CC structure, consisting of three main components, namely a 2-oxoacid CC dehydrogenase (E1), a dihydrolipoamide acyltransferase (E2), CC and dihydrolipoamide dehydrogenase (E3). CC -!- The reaction catalyzed by this system is the sum of three activities: CC EC 1.2.4.4, EC 2.3.1.168 and EC 1.8.1.4. CC -!- The system also acts on (S)-3-methyl-2-oxopentanoate and 4-methyl-2- CC oxopentanoate. //